#include <iostream>
#include <cstdio>
using namespace std;
int n,m,x,y,dp[100][100];
int main()
{
    freopen("pj024.in","r",stdin);
	freopen("pj024.out","w",stdout);
	cin>>n>>m>>x>>y;
	dp[x][y]=dp[x-1][y-2]=dp[x-1][y+2]=dp[x+1][y-2]=dp[x+1][y+2]=dp[x-2][y+1]=dp[x-2][y-1]=dp[x+2][y-1]=dp[x+2][y+1]=-1;
	for(int i=0;i<=m;i++)
	{
		if(dp[0][i]!=-1)
			dp[0][i]=1;
		else
		{
			for(int j=i;j<=m;j++)
				dp[0][j]=-1;
			break;
		}
	}
	for(int i=0;i<=n;i++)
	{
		if(dp[i][0]!=-1)
			dp[i][0]=1;
		else
		{
			for(int j=i;j<=n;j++)
				dp[j][0]=-1;
			break;
		}
	}
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
			if(dp[i][j]!=-1)
			{
				if(dp[i-1][j]==-1&&dp[i][j-1]==-1)
					dp[i][j]=-1;
				else if(dp[i-1][j]!=-1&&dp[i][j-1]==-1)
					dp[i][j]=dp[i-1][j];
				else if(dp[i-1][j]==-1&&dp[i][j-1]!=-1)
					dp[i][j]=dp[i][j-1];
				else if(dp[i-1][j]!=-1&&dp[i][j-1]!=-1)
					dp[i][j]=dp[i-1][j]+dp[i][j-1];	
			}
	cout<<(dp[n][m]==-1?0:dp[n][m]);
	fclose(stdin);
	fclose(stdout);
	return 0;
}
